Patent GB-1038074-A (GB)
Title: Traffic light control systems
IPC: G08G1/081
Filed: 1963-02-05
Abstract: 1,038,074. Road traffic signals. RAD-OLITE Inc. Feb. 5, 1963 [Sept. 26, 1962], No. 4639/63. Heading G4Q. A number of traffic controllers of the type described in co-pending Specification 1,038,071 are interconnected to provide a centralized control to vary the timing cycle in accordance with rush hour traffic, and a centralized " walk/don't walk " operation, or to monitor operation of the controllers. Associated with each controller is a decoder and supervisory unit of Fig. 4 which interprets information from a master controller of Fig. 3 via lines 156, Fig. 2 (not shown), and reports back to the master controller any malfunction of the controller. Such malfunction is displayed on the apparatus of Fig. 3 in conjunction with the apparatus of Fig. 5. In order to inter-relate the timing to provide wave operation the master controllers may be interconnected as indicated in Fig. 6. Provision is also made for telephone communication to the central control station, Fig. 8 (not shown). The master controller of Fig. 3 comprises a timer circuit similar to that of Fig. 1, in which the latching relay controlled by coils 181, 182 is moved alternately up and down under the action of the timer valve 162, and alternately energize and de-energize relay 219. With relay 219 de-energized (phase 1), a positive potential is connected to terminal 192, and a negative potential to terminal 194. With relay 219 energized (phase 2), these potentials are reversed. At the same time either lamp 237 or lamp 238 is lit to indicate the phase. Terminals 192, 194 are connected to lines 156, Fig. 2 (not shown), and relays 207, 211 are provided to indicate abnormal conditions on these lines. If the connection between terminals 192, 194 is open circuit, relay 211 is de-energized, lamp 247 is lit and ground potential is applied to terminal 254. If the connection becomes short circuit, relay 207 operates lighting lamp 251, again connecting ground potential to terminal 254, and also putting a limiting resistor 253 in circuit. The terminals 254 of all the master control units are connected to a common relay 258, Fig. 5, which becomes energized to light a common lamp 266 and sound a buzzer 267. The buzzer may be silenced by operating switch 269, and sounds again on clearing the fault not until the switch is reset. Remote control.-In order to control the intersection of lights from the master controller, the terminals 192, 194, Fig. 3, are connected to terminals 192<1>, 194<1>, Fig. 4, of a decoder and supervising unit at the intersection. On switching on the power supply, relay 279 operates and the terminals 192<1>, 194<1> are connected together over a first path including relay 294 and a diode 292 poled to conduct when terminal 192<1> is positive and terminal 194<1> negative, and over a second path including relay 303 and a diode 301 poled to conduct when terminal 192<1> is negative and terminal 194<1> positive. Thus when terminal 192<1> is positive (phase 1) relay 294 is energized and a voltage is fed to terminal 151 which is connected to the corresponding terminal of Fig. 1. Relay 44, Fig. 1, then operates to set the intersection controller to its phase 1 state. Similarly in the phase 2 state relay 303 operates to correct a potential to terminal 149 for operating relay 67, Fig. 1, to set the intersection controller to its phase 2 state. Supervisory equipment.-The circuit of Fig. 4 also performs as number of supervisionary functions. Loss of the A.C. power supply results in relay 279 releasing and terminals 192<1>, 194<1> are interconnected over a path including diode 314. Thus during phase 1 diode 314 conducts, short circuiting terminals 192<1>, 194<1> to light lamp 251, Fig. 3, and during phase 2 the diode does not conduct, terminals 192<1>, 194<1> are open circuit and lamp 247, Fig. 3, is lit. If synchronism is lost between the master controller and the intersection controller, then lamp 204 lights during phase 1, and lamp 251 during phase 2. Relay 317 is operated during the time the master controller is in phase 1 connecting terminal 126 to relay 288, and is released during the time the master controller is in phase 2 connecting terminal 5 to relay 288. These terminals are associated with the cross street green lights 103, Fig. 1, and main street green lights 1 respectively, and connect an energizing potential to relay 288 if the intersection controller is out of phase with the master. Operation of relay 288 connects diode 324 between terminals 192<1>, 194<1> resulting in an open circuit when 192<1> is positive lighting lamp 247 and a short circuit when 194<1> is positive lighting lamp 251. In order to indicate failure of a red light at the intersection, the terminal 94 of Fig. 1 is disconnected from the lamps 96 and connected to terminal 94, Fig. 4, lamps 96 and connected to terminal 332, Fig. 4, terminals 18, 19, Fig. 1, are connected to corresponding terminals in Fig. 4 and jumper 20, Fig. 1, is removed. Failure of one of the red lights reduces the current through one of the primary windings 333, 341 of transformer 334 and relay 353 releases energizing relay 357 and relays 338 to disconnect the power supply from the unit of Fig. 1 and to connect flasher 379 to the remaining red lights. A connection is also made to pulse relay 288 at the flashing rate to give a distinctive indication on the lamps 247, 251. When maintenance work is necessary ganged switches 398, 320, 346 are operated to disconnect the A.C. supply and to flash the main street amber and cross street red lights. The lights may be remotely switched to their flashing condition by operation switch 411, Fig. 3. Relay 217 then operates during the next phase 1 period. Switch 234 is then operated to disconnect the A.C. supply with the controller in the phase 1 state. Relay 217 operating also connects the negative voltage to terminal 194 and a larger than normal positive voltage to terminal 192. In the unit of Fig. 4 terminal 426, 426<1> and 428, 428<1> respectively are stopped and resistor 427 is disconnected. Relay 431 is adjusted to be operated by the high positive voltage on terminal 192, but not the normal, and thus operates energizing relay 348 which closes contacts 315/442 and connects the flasher to the main street amber and across the street red light. Instead of the manual switches, the control may be effected automatically by a time clock 446, Fig. 5, which operates relay 449 during a phase 1 period. Walk/don't walk.-Operation of manual switch 468, Fig. 3, energizes relay 217 during the phase 2 period to connect the large positive voltage to terminal 194 and the negative voltage to 192. A relay 466 which operates on the large voltage but not the normal is connected across terminals 462, 463 in place of resistor 464 and operates during the phase 2 period to display a " walk " signal to permit pedestrians to cross the road. Flow operation.-To ensure traffic flow at a predetermined speed along a route having intersections C, D, E, F, the relevant Fig. 3 units are interconnected as shown. Assume all controllers are in their phase-2 state with relays 563, 514, 515 energized then a negative potential is applied via terminals 478 to cut off valves 162 in units D, E, F. Unit C times out switching to phase 1 to energize relay 486 and capacitor 493 discharges until valve 492 conducts to energize relay 489. A negative potential is then applied to terminal 477 in the D unit, energizing relay 177 to switch it to phase 1. Relay 563 then releases allowing unit D to time out until valve 162 conducts switching it back to phase 2. Capacitor 493 also discharges until valve 492 conducts to energize relay 489, resulting in the E unit being switched. The operation then repeats itself through all the units. Reversal of flow is obtained by energizing relays 471, 472, 473, the units then being energized in the reverse sequence. Computer control.-The units of Fig 3 may if desired be controlled by a computer in accordance with traffic density, Fig 9 (not shown), the computer feeding signals to operate coils 181, 182 of the latching relay and to cut off the timing valve 162.